SATHEE: Shortcut Methods

Moving Coil Galvanometer Shortcuts and Tricks

To determine the current sensitivity of a galvanometer, divide the full-scale deflection current by the number of divisions on the scale.
$$Current Sensitivity (μA/div) = \frac{Full\text{ }Scale\text{ }Deflection\text{ }Current\text{ }(μA)}{Number\text{ }of\text{ }Divisions\text{ }on\text{ }the\text{ }Scale}$$
To determine the voltage sensitivity of a galvanometer, divide the full-scale deflection voltage by the number of divisions on the scale.
$$Voltage Sensitivity (mV/div) = \frac{Full\text{ }Scale\text{ }Deflection\text{ }Voltage\text{ }(mV)}{Number\text{ }of\text{ }Divisions\text{ }on\text{ }the\text{ }Scale}$$
To calculate the resistance of a galvanometer, use the ohmmeter range of a multimeter to measure the resistance between the terminals of the galvanometer.
To calculate the inductance of a galvanometer, use an inductance meter to measure the inductance of the galvanometer coil.
To calculate the spring constant of a galvanometer, use a force gauge to measure the force required to deflect the coil by a known distance.

To determine the range of an ammeter, read the maximum current value indicated on the scale.
To determine the accuracy of an ammeter, read the accuracy percentage indicated on the meter face or in the specifications.
To determine the internal resistance of an ammeter, use the ohmmeter range of a multimeter to measure the resistance between the terminals of the ammeter.
To determine the shunt resistance of an ammeter, use the ohmmeter range of a multimeter to measure the resistance of the shunt resistor.

To determine the range of a voltmeter, read the maximum voltage value indicated on the scale.
To determine the accuracy of a voltmeter, read the accuracy percentage indicated on the meter face or in the specifications.
To determine the internal resistance of a voltmeter, use the ohmmeter range of a multimeter to measure the resistance between the terminals of the voltmeter.
To determine the multiplication factor of a voltmeter, use the ohmmeter range of a multimeter to measure the resistance between the terminals of the voltmeter in the different voltage ranges and compare it with the resistance in the lowest voltage range.
$$Multiplication\text{ }Factor =\frac{Resistance\text{ }at\text{ }Higher\text{ }Voltage\text{ }Range}{Resistance\text{ }at\text{ }Lowest\text{ }Voltage\text{ }Range}$$

To calculate the potential energy of a dipole in an electric field, calculate the angle between the dipole moment and the electric field using the cosine function.
$$\cos\theta = \frac{\overrightarrow{p} \cdot \overrightarrow{E}}{|\overrightarrow{p}||\overrightarrow{E}|}$$
The dipole moment is the product of the charge and the distance between the charges, and the magnitude of the electric field is the electric force per unit charge.
Substitute these values into the formula (U = -pE\cos\theta) to find the potential energy of the dipole.